Christopher F. Pope

The effect of mode of agitation and type of plastic bag on storage characteristics and in vivo kinetics of platelet concentrates

We studied the characteristics of platelet concentrates stored for 5 days at 22°C. Platelets were prepared in three plastic bags (PL 732, PL 1240, and CLX) and stored on one of four platelet agitators, 1‐ or 6‐rpm elliptical and 2‐ or 6‐rpm circular rotators. A total of 76 studies were divided among 12 groups, each group being composed of a different storage bagrotator combination. In vivo recovery and survival were calculated using Indium‐111 oxine‐labeled platelets injected into autologous volunteers. Platelet recovery was assessed at 2 hours postinjection or as the y‐intercept of the multiple‐hit model survival curve. Survival was calculated using linear, exponential, and multiple‐hit computer models. Linear T 1/2 also was calculated as an index of platelet survival.

Magnetic resonance imaging of the surgically repaired meniscus: Six-month follow-up

The appearance and rate of healing of sutured meniscal repairs in 17 patients were evaluated using magnetic resonance scans. While prior studies in animals and humans (1-4) suggest that complete healing can occur as early as 6 wk postoperatively, we found that at 7 wk 15/15 patients demonstrated meniscal defects at the site of repair. At 6 mo, 11/11 patients showed persistent signal abnormalities. Two patients scanned at 11-12 mo also had defects at the site of repair. Therefore, complete meniscal healing appears not to occur as early as previously believed. This may affect decisions regarding the type of suture material used, the surgical treatment of associated injuries and the postoperative rehabilitation regimen. As defects may be present for relatively long periods of time following meniscal repair, caution must be exercised when attempting to diagnose new or recurrent tears in these patients.

The clinical significance of Stage 2 meniscal abnormalities on magnetic resonance knee images

The Stage 2 meniscal abnormality was subdivided into Stage 2A--linear abnormal signal not contacting an articular surface, Stage 2B--abnormal signal in contact with the articular surface on a single image, Stage 2C--extensive wedge-shaped signal abnormality not in contact with an articular surface. Arthroscopy showed tears in 2A 3%, 2B 0%, 2C 50%. Complete tears should only be diagnosed if contact is seen on more than one image. Many Stage 2C menisci may have tears.

Radiographic differentiation between different etiologies of pulmonary edema.

We compared the plain chest radiographs of critically ill patients who had different types of pulmonary edema and evaluated the radiographs according to a standardized score sheet of findings. We included 94 total cases of pulmonary edema: 49 with cardiogenic, 33 with permeability, and 12 with renal/overhydration pulmonary edema. Patients with cardiogenic edema had enlarged hearts, vascular engorgement, septal lines, and absence of air bronchograms significantly more often than patients with permeability pulmonary edema. Renal/overhydration patients had enlarged hearts significantly more often than patients with permeability edema. There were no other statistically significant differences. Heart size and presence or absence of septal lines could have been used to distinguish cardiogenic and permeability edema in 83% of cases.

The detection of pulmonary emboli by magnetic resonance imaging. Evaluation of imaging parameters.

The authors studied the influence of gating, cardiac cycle, and timing of rephasing gradients upon the detection of pulmonary emboli by MRI. Serial single-section MR images were obtained in normal dogs and dogs with experimental pulmonary emboli. Images with cardiac gating, respiratory gating, and ungated images were obtained. Cardiac gating in systole and late magnetization rephasing had the best diagnostic accuracy. Gated images were clearly superior to ungated; with combined cardiac and respiratory gating, sensitivity was 82% and specificity 88%. These results are sufficiently promising to warrant further studies.

Technical variables influencing the detection of acute deep vein thrombosis by magnetic resonance imaging

To establish which technical variables influence the detection of deep vein thrombosis by magnetic resonance imaging, 2 dogs, 5 normal volunteers and 17 patients were studied using a 1.5 T whole-body system. A sequential slice gradient echo acquisition (TR 25, TE 13, 0 = 30 degrees, 2 NEX, flow compensation rephasing gradients) in the axial plane was found to be optimal for detecting venous thrombosis. Thus, when using appropriate technique, MRI may identify deep venous thrombosis accurately. It may also allow the diagnosis of conditions which may simulate venous thrombosis clinically since the most common of these, ruptured Bakers cyst, cellulitis, muscle tear, hematoma and external venous compression are all readily identified by MRI.

Alterations in MR relaxation of normal canine gallbladder bile during fasting

Abstract The correlation between the concentration and proton relaxation of bile was studied by examining sequential changes in the MR image appearance and relaxation times of gallbladder bile during a 24-h fasting period in dogs. Bile relaxation times computed from images showed progressive shortening during the first 4–8 h of fasting: T1 decreased from 500–900 ms to 250–400 ms and T2 from 130–190 ms to 70–100 ms at 0.15 T. Similar in vitro results at 0.47 T were obtained on aspirated bile samples. Relaxation times of gallbladder bile remained longer than those of the liver, and we conclude that in general the gallbladder will appear less intense than the liver on T1-weighted images (with short enough TE) and more intense on T2-weighted images regardless of the bile concentration. The liver/gallbladder contrast may reverse in a normal subject during fasting for pulse sequences combining both T1 and T2 effects, which may be explored for the possible visual detection of abnormal gallbladder function on an image.

Errors in the assessment of the efficacy of MRI pulse sequences

The effects of the echo delay TE on contrast in saturation recovery MRI have been analyzed both theoretically and with experimental brain scans. It is demonstrated that the influence of the TE values offered as minimal values by all major current equipment manufacturers is not insignificant, but produces a degree of T2 weighting that considerably degrades the useful contrast that could be obtained from T1 weighted studies. Consequently, conclusions drawn about the relative performances of T1 and T2 weighted sequences may be incorrect if based on saturation recovery images obtained with inappropriate echo times.

The use of Indium-111 Platelet Scintigraphy in Man: Comparisions with in Vitro Tests and in Vivo Platelet Function — A Five — Year Experience

This paper reports data collected from 540 patients between July 1978 and July 1983. For the first four years, studies were performed at the Hospitals of the University of Oklahoma Health Science Center and then continued in the last year at Yale University School of Medicine and at the West Haven VA Medical Center. A small number of patients have been studied at St. Raphael’s Hospital in New Haven, Connecticut.